The redo log buffer is a circular buffer in the SGA that stores redo entries describing changes made to the database.A redo record is a data structure that contains the information necessary to reconstruct, or redo, changes made to the database by DML or DDL operations. Database recovery applies redo entries to data files to reconstruct lost changes.The database … Read more
The shared pool caches various types of program data.For example, the shared pool stores parsed SQL, PL/SQL code, system parameters, and data dictionary information. The shared pool is involved in almost every operation that occurs in the database. For example, if a user executes a SQL statement, then Oracle Database accesses the shared pool. This section includes the following … Read more
Automate RMAN Backup using Shell Script In a real environment, you will not manually trigger all the Oracle database backups. You need an automated mechanism to trigger RMAN backups. Create directory On your database server, create a directory to hold RMAN backups and all related files. All the RMAN backups, logs and backup scripts are … Read more
A) Recovery Point Objective(RPO) A recovery point objective (RPO) is the maximum length of time permitted that data can be restored from, which may or may not mean data loss. RPO concerns with data. It is the amount of data you are willing to lose when the failure occurs in your database system. Usually people … Read more
1. Verify that client networking connections are functional. Clients must be able to login to sql*plus with username/password/host string (where host string is the alias created for the specific sid). i.e.: username: <dbuser> password: <dbpassword> host string: <connectstring> -or- username: <dbuser>/<password>/<connectstring> 2. Login as oracle user and add scripts at the end of the glogin.sql … Read more
Once the ASM instance is started, all the basic background processes, as well as some that are specific to the operation of ASM, are started. On Linux, the ASM processes can be listed using the following command: Some of the more important ASM background processes: ARBx These are the slave processes that do the rebalance … Read more
Row Chaining Occurs when the row is too large to fit into one data block when it is first inserted. In this case, Oracle stores the data for the row in a chain of data blocks (one or more) reserved for that segment. Row chaining most often occurs with large rows, such as rows that … Read more
The PGA is memory specific to an operating process or thread that is not shared by other processes or threads on the system. Because the PGA is process-specific, it is never allocated in the SGA. The PGA is a memory heap that contains session-dependent variables required by a dedicated or shared server process. The server … Read more
The UGA is session memory, which is memory allocated for session variables, such as logon information, and other information required by a database session. Essentially, the UGA stores the session state. If a session loads a PL/SQL package into memory, then the UGA contains the package state, which is the set of values stored in … Read more
11g database – Datafile created with extra blank space similar to existing datafile. Please note that oracle database will not allow exact datafile name, this happens when user put space character in file name, so it looks like duplicate filename but it will be different. So user wanted to rename such files, below is the … Read more